package tips.p_1000.p151_200;

/**
 * 给你一个由 '1'（陆地）和 '0'（水）组成的的二维网格，请你计算网格中岛屿的数量。
 * 岛屿总是被水包围，并且每座岛屿只能由水平方向和/或竖直方向上相邻的陆地连接形成。
 * 此外，你可以假设该网格的四条边均被水包围。
 * <p>
 * 示例 1：
 * 输入：grid = [
 * ["1","1","1","1","0"],
 * ["1","1","0","1","0"],
 * ["1","1","0","0","0"],
 * ["0","0","0","0","0"]
 * ]
 * 输出：1
 *
 * @author hc
 */
public class Demo200 {

    public int numIslands(char[][] grid) {

        int landNum = 0;
        for (int i = 0; i < grid.length; i++) {
            for (int j = 0; j < grid[0].length; j++) {
                if (grid[i][j] == '1') {
                    dfs(grid, i, j);
                    landNum++;
                }
            }
        }

        return landNum;
    }

    private void dfs(char[][] grid, int i, int j) {

        if (i < 0 || i >= grid.length || j < 0 || j >= grid[0].length || grid[i][j] != '1') {
            return;
        }
        grid[i][j] = '2';
        dfs(grid,i+1,j);
        dfs(grid,i-1,j);
        dfs(grid,i,j+1);
        dfs(grid,i,j-1);
    }
}
